Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (174 page)

   CT scan also gives information in instances where staging a suspected neoplasm has clinical significance (see Cancer Head of the Pancreas).

   In patients for whom mass lesions (i.e., malignancy, abscess) are suspected or where technical limitations make ultrasound difficulty to interpret, CT is preferred.

   
Percutaneous transhepatic cholangiography (PTC)
: The technical success rate of this procedure is approximately 90–99%. Its use is limited by a major complication rate of 3–5% and has been largely supplanted by endoscopic retrograde cholangiopancreatography (ERCP). ERCP offers a lower complication rate than PTC and provides a greater number of therapeutic options (stone extraction, stent placement).

   This test could reasonably be used in patients with a high likelihood of extrahepatic obstruction (e.g., those who have had recent biliary surgery, symptoms of cholangitis, palpable gallbladder, pain or fever, pancreatitis).

   When palliation is the primary intent, ERCP is an appropriate initial procedure.

   
Magnetic resonance cholangiopancreatography (MRCP)
is a radiologic technique that produces images of the pancreaticobiliary tree, which are similar in appearance to those obtained by invasive methods. It appears to have diagnostic accuracy similar to that of ERCP.

   MRCP is indicated for patients with allergies to iodinated contrast media and patients with altered anatomy (i.e., secondary to surgical procedures or congenital abnormalities).

   ERCP has advantages over MRCP, which include the ability to perform therapeutic interventions, perform manometry or endoscopic ultrasound, directly visualize the ampulla, and biopsy lesions.

DISEASES ASSOCIATED WITH JAUNDICE

CONJUGATED HYPERBILIRUBINEMIA/HEPATOCELLULAR JAUNDICE

CIRRHOSIS OF THE LIVER

   Laboratory Findings

   
Bilirubin
: Serum levels are often increased; may be present for years. Fluctuations may reflect liver status due to insults to the liver (e.g., alcoholic debauches). Most bilirubin is of the unconjugated type unless cirrhosis is of the cholangiolitic type. Higher and more stable levels occur in post–necrotic cirrhosis; lower and more fluctuating levels occur in Laennec cirrhosis. Terminal icterus may be constant and severe. Urine bilirubin is increased; urobilinogen is normal or increased.

   
AST
: Serum levels are increased (<300 U) in 65–75% of patients. Serum ALT is increased (<200 U) in 50% of patients. Transaminases vary widely and reflect activity or progression of the process (i.e., hepatic parenchymal cell necrosis).

   
ALP
: Serum levels are increased in 40–50% of patients.